Conventional write heads may be used in conjunction with magnetoresistive (MR) heads. Together, the MR head and the write head can write to and read from magnetic recording media. The conventional write head includes a first pole, a second pole, and one or two coil layers. Each of the coil layers has several turns. The first and second poles are separated by a write gap. Magnetic flux through a portion of the write gap is used to write to the magnetic recording media. The write head is covered by an overcoat layer.
In order to generate the magnetic flux, current is passed through the coil layers. The coil layers are electrically isolated from the first pole, from the second pole, and from each other. However, the coil layers are magnetically coupled to the second pole. Current driven through the coil layers generates a magnetic field. Because the coil layers are magnetically coupled to the second pole, the second pole directs the magnetic flux generated by the coil layers to the write gap. The first pole is the return of the flux path.
The material used to electrically insulate the coil layers is typically an organic photoresist. When the write head is fabricated, photoresist is spun onto the first coil layer. The second coil layer is provided on the layer of photoresist. A second layer of photoresist is then spun onto the second coil layer. The second pole is plated on the second layer of photoresist.
Although the organic photoresist is capable of electrically insulating the coil layers, the use of photoresist causes a variety of problems. Because the photoresist is used to insulate the coil layers, the photoresist layers are made relatively thick. For example, in one conventional head the photoresist is approximately three microns thick. As a result, the top of each layer of photoresist is relatively flat in comparison to the shape of each of the coil layers being insulated. Because the photoresist is relatively thick, the magnetic coupling between the coil layers and the poles is reduced. Consequently, more current is required to produce the desired field for writing to the magnetic recording media. In addition, the photoresist has a relatively large coefficient of thermal expansion. During fabrication, the temperature of the write head increases greatly. Changes in temperature cause the photoresist layer to expand. This may cause cracking in portions of the write head, including the overcoat layer.
Accordingly, what is needed is a system and method for providing a write head in which the problems due to the insulation of the coil layers are reduced. The present invention addresses such a need.